This invention relates to a magnetic recording/reproducing apparatus, and is more particularly suitable to apply to a floppy disc device for example.
Hitherto, in this type of floppy disc device, the desired data are recordable and reproducible by use of an integrated control circuit 2 and a write/read circuit 4 as illustrated in FIG. 1.
To be specific, in a floppy disc device 1, a control command COMD is inputted to the control circuit 2 from, e.g., a computer, and, at the same time, input data DATA are also inputted thereto.
The control circuit 2 changes over an operation mode of the floppy disk device 1 in conformity with the control command COMD and drives mechanical drive circuit (unillustrated) according to the necessity.
At this time, in the recording mode, the control circuit 2 causes a fall in the level of an erase control signal XERS and outputs it to the write/read circuit 4, thereby driving an erase magnetic head 6A for a predetermined period.
Further, the control circuit 2 simultaneously causes a fall in the level of a write control signal XWGO to set the write/read circuit 4 in the recording mode. Thereafter, the control circuit 2 sequentially outputs predetermined record data XWDO.
Corresponding to this operation, the write/read circuit 4 supplies, when the erase control signal XERS has fallen, a predetermined DC current to the erase magnetic head 6A.
The erase magnetic head 6A is herein constructed integrally with a recording/reproducing magnetic head 6B. The erase magnetic head 6A is arranged to scan a floppy disc in advance of the recording/reproducing magnetic head 6B, thereby erasing the recorded data beforehand with respect to an area scanned by the erasemagnetic head 6A during a falling period of the erase control signal XERS.
Further, the write/read circuit 4 drives, when being set in the recording mode, the recording/reproducing magnetic head 6B by a record current IW determined by an externally attached record current setting resistor 8 in accordance with the record data XWDO sequentially inputted.
In the floppy disc device 1, the input data DATA are sequentially thereby recordable in a predetermined format.
Namely, as illustrated in FIGS. 2A to 2D, in the floppy disc device 1, the input data are recorded on respective recording tracks TR (FIG. 2A) in sector units. At this time, predetermined gaps 2 and 3 are formed in front of and behind the respective input data.
When recording new data on a floppy disc upon which data have already been recorded, i.e. when re-writing data, erase the current to erase magnetic head 6A rises in a portion of the area of the gap 2, and simultaneously the recording/reproducing magnetic head current is increased in a portion of the area of the gap 2, by the falling of write control command WEN (FIG. 2B).
With this operation, in the floppy disk device 1, after the recording/reproducing magnetic head 6B has sequentially recorded the input data DATA in the area erased by the erase magnetic head 6A, the recording operation stops in an area of the gap 3 (FIG. 2C). New input data (indicated by a symbol ND) is recorded between the previously recorded data (indicated by a symbol OD).
In the case of driving the erase head 6A and the recording/reproducing magnetic head 6B in this manner, however, the erase magnetic head 6A erases an extra data area, in which no new data are subsequently recorded by scanning the area ARE in which the erase magnetic head 6A proceeds with respect to the recording/reproducing magnetic head 6B.
Hence, it follows that the an area in which no data is recorded exists on the recording track TR. It is difficult to obtain a regenerative signal SRF from this area (FIG. 2D).
For this reason, in the floppy disc device 1, it is hard to extract a regenerative clock pulse during the period for which the recording/reproducing magnetic head 6B scans the above-mentioned area when effecting the reproduction. This presents such a problem that the operation of a regenerative system as a whole becomes unstable.